(1) Field of the Invention
The present invention relates to electronic pulse dialers and more particularly to current regulated pulse dialers. A current source connected to an electronic pulse dialer provides high impedance to a telephone line during transmission and interpulse pause conditions.
(2) Description of the Prior Art
Pulse dialers have been adapted to telephones to provide pushbutton operation while retaining dial pulse signaling. To provide this feature, a pulse dialer is connected across a telephone loop and operates to output pulse signals by breaking and closing the loop. However since the pulse dialer is connected across the loop it presents a low impedance during transmission open circuit pulsing conditions. Since there is not a true open loop condition during the break period of outpulsing, dial pulse distortion (low amplitude pulses) results causing a reduction in the usable loop length. Similarly the pulse dialer presents a low impedance across the loop during transmission conditions, thus shunting speech signals and causing degradation of transmission characteristics. This problem is inherent with electronic pulse dialers and has only been overcome through the use of relays to break the loop and provide true open circuit conditions.
Accordingly, it is the object of the present invention to provide a novel, low cost and highly reliable means of providing open circuit conditions to a telephone line during transmission and interpulse pause conditions.